Q: In an article about the Gilroy, CA, shooting, the NY Times says investigators “also are continuing to scrub various electronic devices and trying to learn if he had any help carrying out the shooting.” Isn’t this an incorrect use of “scrub,” which I’d always understood to mean, in this context, to make data unrecoverable?
A: We’ve never seen this use of “scrub” before. When used in relation to computers and other electronic devices, “scrub” means either to clean or to erase, rather than to examine for evidence.
We looked at 10 standard British and American dictionaries, and only one, The American Heritage Dictionary of the English Language, has definitions for “scrub” in computer senses. Here they are, along with the dictionary’s examples:
“a. To maintain the integrity of by finding and correcting errors: software that automatically scrubs stored data.
“b. To erase in such a way as to render unrecoverable: scrubbed the laptop’s hard drive to destroy incriminating evidence.”
We’re surprised that only one standard dictionary has picked up on these usages. Both of those senses of “scrub” can be found in specialized reference books. Here are examples of each definition of the verb as used in computer science:
“To examine a large amount of data and eliminate duplicate or unneeded items” (McGraw-Hill Dictionary of Scientific & Technical Terms (2003). “To wipe information off a disk or remove data from store” (Simon Collin’s Dictionary of Computing, 2009).
We haven’t found any dictionary or glossary that defines “scrub” as to search for evidence.
In its nontechnical usage, “scrub” has similar senses: (1) to vigorously clean something by rubbing, as in “he scrubbed the kitchen floor,” and (2) to cancel or eliminate, as in “the launch was scrubbed” or “his horse was scrubbed from the race.”
The Oxford English Dictionary, an etymological dictionary based on historical evidence, has no entries for computer senses of “scrub,” at least not yet. As for less technical uses, the OED describes the verb as Germanic in origin and “of obscure history.”
The verb was first recorded in Middle English writing in the 1300s, when it meant to curry-comb a horse, a sense that may have come from Middle Low German or Middle Dutch terms for scraping or scrubbing.
In its modern sense—to clean by hard rubbing—“the word may perhaps have been re-imported from Dutch as a nautical term,” the OED suggests.
This current sense of “scrub” was first recorded in the 16th century, at a time when Holland was a major naval power and many Dutch nautical words came into English. In those days, the English word meant “to clean (esp. a floor, wood, etc.) by rubbing with a hard brush and water.”
However, the earliest OED example, from 1595, uses the term figuratively. It’s from a contemporary account of Sir Francis Drake’s final, disastrous expedition against Spain in the West Indies:
“If part of our companie had been sent thither upon our first arrival at Rio de la Hacha, doubtles we had done much goode, but now they [the Spaniards] had scrube it very bare.” (From Sir Francis Drake His Voyage, 1595, a contemporary narrative written by a passenger, Thomas Maynarde. In December 1595, Drake’s men landed at the city only to find that the Spanish had “scrubbed” it bare—that is, removed everything of value.)
The dictionary’s earliest use of “scrub” meaning to cancel or eliminate is from the early 19th century, and is found in the private writings of Sir Walter Scott:
“If I were alone, I could scrub it [a visit to London], but there is no doing that with Anne” (a diary entry written March 22, 1828, and first published in The Journal of Sir Walter Scott, 1941).
The dictionary defines the word in this sense as “to cancel, scrap, call off; to eliminate, erase; to reject, dismiss.” It adds that this usage was “reinforced by the popularity of the expression amongst servicemen in the war of 1939–45.”
Oxford includes several WWII uses, both British and American, including this enlightening passage from a letter to the editor of the Spectator. The letter, from a British naval officer, ran on May 25, 1945, in response to a review of a book on air force slang:
“The author can possibly justify the inclusion of the term ‘scrub,’ meaning ‘to cancel,’ in a collection of R.A.F. slang. The expression is in common use in the Royal Navy and has been for many generations. It derives from the days when all signals and orders were written on a slate. When the signals were cancelled or orders executed, the words on the slate were ‘scrubbed out’ or, equally correctly ‘washed out.’ ”
[Note: Two readers have called our attention to another use of “scrub” in a technical sense, a usage that apparently comes from the days of reel-to-reel tape players. As one commented: “Audio and video scrubbing is moving quickly through a recording (fast forward or fast rewind) while the recording plays in order to find a specific spot in the recording. It does not seem like a stretch to me to go from searching an audio or video recording for something specific to searching data recorded on a computer drive for something specific.”]